The present invention relates to a method for preparing a mold for continuous casting, prior to starting the casting process proper.
The surface level of the liquidous material e.g. steel in a mold for continuous casting is usually covered by a slag producing substance. This substance is usually applied as a powder and has a melting point below the melting point of the steel. In a refinement of this method, (U.S. Letters Patent 3,642,052) it has been proposed to use two different kinds of casting powders which differ as to melting point, and they are applied sequentially to the surface of the molten steel so that slag is produced rapidly at first followed by a slower production by the higher melting powder.
The application and utilization of powders specifically and continuous casting generally poses relatively few problems during regular operation as compared with start up. Particularly, the period from the initial filling of the mold up to the beginning of casting proper is quite difficult to control. Cracks and fissures develop in the first portion immediately adjacent to the stool, and even further up, rendering a sizeable portion of the ingot useless until in fact stabilized -- stationary casting conditions have developed.